I don't know what numbers you are looking for but... I have a 1984 c30 from the back of the brake drum to the back of the brake drum is 55 in cl of the spring mount is 40 " cl of the axle to yoke is 18 " looking at my 1959 3600 I have 52 " brake to brake 41.5" cl of spring to cl. 18" cl of axle to yoke. This is a dual wheel rear so outside of wheel to outside is 90" if that will fit under your flatbed. I looked at 3/4 ton rears awhile ago trying for a better gear they were close but I had concerns about driveshaft length/universil joint and weather the brakes would work well. If you need a specific measurement let me know.